U.S. patent application number 10/648157 was filed with the patent office on 2004-03-25 for sandwich-molded guide for transmission device.
Invention is credited to Konno, Masahiko.
Application Number | 20040058763 10/648157 |
Document ID | / |
Family ID | 28786862 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058763 |
Kind Code |
A1 |
Konno, Masahiko |
March 25, 2004 |
Sandwich-molded guide for transmission device
Abstract
In a sandwich molded guide for an endless, flexible,
transmission medium such as a silent chain or roller chain, a slide
rail and a rail support are sandwich-molded. The slide rail and the
rail support are integrally molded from a high strength first
polymer resin and the entire outer surface of the integrally molded
structure is covered with a wear-resistant second polymer resin. A
lightweight and inexpensive sandwich-molded guide, having excellent
mechanical strength and wear resistance, can be easily molded in a
single mold in a short molding cycle time, and can be readily
recycled.
Inventors: |
Konno, Masahiko; (Osaka,
JP) |
Correspondence
Address: |
HOWSON AND HOWSON
ONE SPRING HOUSE CORPORATION CENTER
BOX 457
321 NORRISTOWN ROAD
SPRING HOUSE
PA
19477
US
|
Family ID: |
28786862 |
Appl. No.: |
10/648157 |
Filed: |
August 26, 2003 |
Current U.S.
Class: |
474/111 ;
474/140 |
Current CPC
Class: |
F16H 7/08 20130101; F16H
7/18 20130101; F16H 2007/0872 20130101; F16H 2007/0812
20130101 |
Class at
Publication: |
474/111 ;
474/140 |
International
Class: |
F16H 007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2002 |
JP |
2002-277405 |
Claims
I claim:
1. A sandwich-molded guide for an endless, flexible, transmission
medium, said guide comprising an elongated slide rail having a
surface along which said transmission medium can travel in sliding
contact along the direction of elongation, and an elongated rail
support, extending along said direction of elongation, for
supporting said slide rail, the slide rail and rail support being
sandwich-molded to form a guide for guiding or maintaining tension
in said transmission medium, wherein said slide rail and said rail
support are integrally molded from a high strength first polymer
resin material, the integrally molded slide rail and rail support
have an outer surface, and said outer surface is entirely covered
by a wear-resistant second polymer resin material.
2. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 1, wherein said first polymer resin
material is a glass fiber reinforced polyamide 66 resin.
3. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 1, wherein said first polymer resin
material is a polyamide 46 resin.
4. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 1, wherein said first polymer resin
material is an aromatic polyamide resin.
5. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 1, wherein said second polymer resin
material is a polyamide 66 resin.
6. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 2, wherein said second polymer resin
material is a polyamide 66 resin.
7. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 3, wherein said second polymer resin
material is a polyamide 66 resin.
8. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 4, wherein said second polymer resin
material is a polyamide 66 resin.
9. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 1, wherein said second polymer resin
material is a polyamide 6 resin.
10. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 2, wherein said second polymer resin
material is a polyamide 6 resin.
11. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 3, wherein said second polymer resin
material is a polyamide 6 resin.
12. A sandwich-molded guide for an endless, flexible, transmission
medium according to claim 4, wherein said second polymer resin
material is a polyamide 6 resin.
Description
FIELD OF THE INVENTION
[0001] This invention relates to guides for endless, flexible power
transmission media, such as silent chains, roller chains and the
like, used for a transmission of power between a driving sprocket
and one or more driven sprockets, for example in the valve timing
apparatus of an automobile engine. The invention relates more
specifically to a plastic guide on which the transmission medium
slides. The guide may be a fixed guide, or a movable guide for
controlling tension in the transmission medium.
BACKGROUND OF THE INVENTION
[0002] In an automobile engine or the like, a guide for a
transmission medium, whether it be a movable guide or a fixed
guide, is generally mounted on an engine block or other frame by
one or more mounting bolts or pins. A movable guide may serve as a
tensioner lever to apply proper tension to the transmission medium
in order to prevent transmission failure due to excess tensioning
or excess loosening of the circulating transmission medium. A fixed
guide, such as a guide rail or the like, maintains the transmission
medium in a required traveling path to prevent vibration noise,
axial run-out, and disengagement, of the circulating transmission
medium from its sprockets.
[0003] A conventional plastic guide 100, shown in FIGS. 6 to 8,
which in this case is a tensioner lever, is molded from a single
synthetic resin. The guide 100 comprises a slide rail body 101, on
the front side of which a traveling transmission chain C slides,
and a rail supporting body 102, arranged on the back side, and
extending along the longitudinal direction of the slide rail body
101. The rail supporting body 102 is provided with a boss 102a,
having a mounting hole 103 for pivotally receiving a mounting pin
or bolt secured to an engine block or other suitable frame. The
rail supporting body 102 also has a tensioner contact portion 102b
for contacting the plunger of a tensioner (not shown). The plunger
controls the pivoting position of the lever, thereby applying
proper tension to the circulating transmission chain and preventing
transmission failure due to excess tensioning or excess loosening
of the chain. Ribs 102c, shown in FIG. 6, reinforce the guide while
serving a weight-reducing function.
[0004] Since the conventional plastic guide 100 is integrally
molded from a single synthetic resin, it was not possible to
maintain the sliding contact properties and wear resistance
required for a slide rail body 101 compatibly with strength
required for the rail support body 101, especially in the high
temperature environment of an automobile engine, which is typically
around 150EC. For example, when the plastic guide 100 is molded
from a plastics material having superior sliding contact properties
and wear resistance, the guide has poor mechanical strength.
However, when the cross-section dimensions are increased to
compensate for the inadequate strength of the selected material,
the thickness of the guide is increased, and the space taken up by
the guide, when mounted on an engine block, is also increased.
[0005] To address the foregoing problem, it has been proposed to
provide a slide rail which includes a support composed of a high
strength synthetic resin, and a slide liner connected to the
support and composed of a wear-resistant synthetic resin. Either
the support or the slide liner is molded, and then used as a mold
for injection molding of the other by use of the one as a mold, as
described in Japanese patent publication No. 2818795 (pages 3 and
4, and FIG. 2). Alternatively, a chain tensioner in which a steel
sheet or the like is insert-molded as a core material has been
proposed in Japanese laid-open patent publication No. Hei. 8-254253
(page 2, FIG. 3). Another proposal, as described in Japanese
laid-open patent publication No. Hei. 9-324839 (page 3-4, FIG. 2),
is to provide a guide rail in which a smooth path liner is fitted
and locked to a carrier by friction.
[0006] In the two-step molding process used to produce the slide
rail disclosed in Japanese patent publication No. 2818795, the
molding cycle time is long. Another problems is that, even if a
dovetail groove is adopted to integrate both synthetic resins, the
strength of the joint between the resins is weak. Still another
problem is that the structure of the mold is complicated, thereby
increasing manufacturing costs.
[0007] In the chain tensioner disclosed in Japanese laid-open
patent publication No. Hei. 8-254253, the difference between
coefficients of thermal expansion of the steel sheet core material
and the plastics material can cause the guide to deform and break.
Moreover, the use of a steel core increases the weight of the
guide. In addition, disassembly of an insert-molded guide, and
recycling of the molded product are difficult.
[0008] In the guide rail disclosed in Japanese laid-open patent
publication No. Hei. 9-324839, in which a previously manufactured
smooth liner is fitted to a carrier by friction, the manufacturing
steps are complicated, and disadvantageous because they increase
manufacturing cost. Further, the guide is subject to breakage, and
not satisfactory from the standpoints of reliability and mechanical
strength.
[0009] Accordingly, the objects of the invention are to solve the
above-mentioned problems encountered in prior art plastic guides,
and to provide a lightweight and inexpensive sandwich-molded guide
for a transmission medium, which has superior mechanical strength
and wear resistance, which can be easily molded using a single
mold, which can be produced in a short molding cycle, and which can
be readily recycled.
SUMMARY OF THE INVENTION
[0010] To address the foregoing objects and the above-described
problems, the sandwich-molded guide in accordance with the
invention comprises an elongated slide rail having a surface along
which an endless, flexible, transmission medium can travel in
sliding contact along the direction of elongation, and an elongated
rail support, extending along the direction of elongation of the
slide rail, for supporting the slide rail. The slide rail and rail
support are sandwich-molded to form a guide for guiding or
maintaining tension in a transmission medium. The slide rail and
rail support are integrally molded from a high strength first
polymer resin material, the integrally molded slide rail and rail
support have an outer surface entirely covered by a wear-resistant
second polymer resin material.
[0011] The first polymer resin is preferably a polyamide 46 resin,
an aromatic polyamide resin, or a glass fiber-reinforced polyamide
66 resin.
[0012] The second polymer resin is preferably a polyamide 66 resin
or a polyamide 6 resin.
[0013] The term "sandwich molding" as used herein refers to a
method of producing a molded product consisting of two kinds of
polymer resin materials formed by simultaneously or substantially
simultaneously injection-molding two kinds of melted polymer resin
materials into a mold corresponding to the outer shape of the
molded product, so that the product is a so-called skin-core,
two-layer, molded product. The sandwich molding method in the
invention can be carried out using a known sandwich molding
injection-molding machine.
[0014] Known sandwich molding injection-molding machines are
provided with various sandwich nozzles. In the case of a sandwich
molding injection-molding machine provided with a parallel type
sandwich nozzle, a torpedo (that is a switching member for
switching between injection of a skin polymer resin material and
injection of a core polymer resin material) is moved forward or
backward so that the rate of injection quantity and injection speed
can be finely controlled for both resins in accordance with the
shape of the molded product. For example, in controlling the
thickness of a skin layer in the invention, when a high-strength
guide is to be molded, strength can be improved by decreasing the
thickness of the skin layer and increasing the volume of the core
layer.
[0015] Various resins may be used as the first and second polymer
resins, but it is preferable that they have chemical affinity and
that there be no large difference between their shrink
characteristics, so that they become strongly fused to each other
at their boundary during sandwich molding.
[0016] Since the slide rail and the rail support are integrally
joined to each other in a fully fused condition, the sandwich
molded guide in accordance with the invention exhibits durability
superior to that of a conventional guide consisting of a single
material or a guide composed of mechanically joined members, and
can guide and/or maintain proper tension in a chain or other
traveling transmission medium over a long period of time.
[0017] The second polymer resin, which covers the entire outer
surface of the slide rail and rail support of the sandwich molded
guide, exhibits excellent wear resistance, and can remain in
sliding contact with a traveling transmission medium over a long
period of time. Additionally, the slide rail and the rail support
are reinforced by the skin composed of the second polymer resin
material. Therefore, the sandwich molded guide exhibits superior
durability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a view for explaining a use embodiment of the
present example;
[0019] FIG. 2 is a perspective view of a sandwich molded guide for
a transmission device, which is an example of the invention;
[0020] FIG. 3 is a cross-sectional view taken on the plane 3-3 in
FIG. 2;
[0021] FIG. 4 is a cross-sectional view taken on the plane 4-4 in
FIG. 2;
[0022] FIG. 5 is a cross-sectional view taken on the plane 5-5 in
FIG. 2;
[0023] FIG. 6 is a front view of a conventional movable guide;
[0024] FIG. 7 is a cross-sectional view taken on the surface 7-7 in
FIG. 6; and
[0025] FIG. 8 is a cross-sectional view taken on the plane 8-8 in
FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] As shown in FIG. 1, a sandwich molded guide 10 is used in
conjunction with a circulating transmission chain C, which is in
driving engagement with a driving sprocket S1 and a pair of driven
sprockets S2. The guide 10, which in this case is used as a movable
guide, is in sliding contact with, and maintains tension in, the
transmission chain C.
[0027] As shown in FIGS. 2 and 3, the sandwich molded guide 10
comprises a rail 11 including an arc-shaped sliding contact surface
11a extending along the traveling direction of a circulating
transmission chain, and a rail support 12 extending longitudinally
along the side of the rail 11 opposite to surface 11a. The rail
support is provided with a boss 12a, having a mounting hole 14 for
pivotal mounting of the guide on an engine block so that it
functions as a movable guide. A tensioner contact portion 12b is
provided for contacting a tensioner (not shown). The tensioner
applies proper tension to the chain to prevent transmission failure
due to excess tensioning or excess loosening of the chain.
Reinforcing ribs 12c serve a reinforcing function and contribute to
weight reduction.
[0028] A high strength polymer resin material, composed of a glass
fiber-reinforced polyamide 66 resin, forms the core layers of the
slide rail 11 and the rail support 12. Both members are fully and
integrally fused together so that the strength required in the high
temperature environment within an automobile engine can be
maintained at a high level for a long period of time.
[0029] Any polyamide resin, such as polyamide 46 resin, aromatic
polyamide resin or the like, or glass-reinforced polyamide 66
resin, which can exhibit high strength over a long period of time,
can be used as the first polymer resin. Glass fiber-reinforced
polyamide 66 resin is the most suitable for use as the first
polymer resin.
[0030] A wear resistant second polymer resin material, composed of
a polyamide 66 resin, may be adopted as the outer layer of the
integrated core layers of the slide rail portion 11 and the rail
supporting portion 12. This second polymer resin material is highly
wear-resistant, and is maintained in sliding contact with the
transmission chain C over a long period of time. In addition, the
second polymer resin reinforces the strength of the slide rail 11
and the rail support 12.
[0031] Any polyamide resin which can exhibit wear resistance while
in sliding contact with the transmission chain C over a long period
of time may be used as the second polymer resin. Polyamide 66 is a
preferred example of a suitable resin for use as the second polymer
resin. Polyamide 46 is another example of a suitable polyamide
resin. On the other hand, glass-reinforced polyamide 66 resin is
not suitable for use as the second polymer resin.
[0032] Preferably the wear resistance of the second polymer is
greater than that of the first polymer, and the strength of the
first polymer is greater than that of the second polymer.
[0033] The guide structure is produced by sandwich molding as
follows. A polyamide 66 resin is first injected, from the sandwich
nozzle of a sandwich molding injection molding machine, into a
single and simple mold corresponding to the outer shape of the
molded guide to be produced. This starts the molding of the
wear-resistant skin layer, which is formed from a second,
wear-resistant, polymer resin over the entire outer shape of the
slide rail 11 and the rail support 12. At the same time, or
substantially at the same time as the start of injection of the
skin layer consisting of a polyamide 66 resin, a glass
fiber-reinforced polyamide 66 resin is injected to form the slide
rail 11 and the rail support 12 as a core layer of high strength
polymer resin material. After the mold is cooled, the molded guide
is removed from the mold, thereby completing a molding cycle.
[0034] In the sandwich-molded guide 10, since the integrally formed
slide rail 11 and rail support 12 is entirely covered with an outer
layer of polyamide 66 resin, the slide rail 11 and the rail support
12 are more strongly joined to each other. Moreover, the surface
layer portions of the boss 12a and the mounting hole 13, provided
at one end of the rail support 12 for mounting the movable guide
10, are injection-molded with a polyamide 66 resin. Accordingly,
the sandwich molded guide 10 can function smoothly, over a long
period of time, as a pivotally movable guide which maintains proper
tension by preventing excessive tensioning or loosening of a
circulating transmission chain C.
[0035] Furthermore, since the entire sandwich molded guide 10
consists of a polymer resin, a significant weight reduction is
achieved, and the molded guide can be easily recycled, without
disassembly and separation of its components, after removal from
the transmission.
[0036] The molding of the slide rail the molding of the rail
support and an integration of the slide rail and the rail support
can be carried out simultaneously or substantially simultaneously
in a single, simple mold and in a single step. Thus, the
sandwich-molded guide in accordance with the invention does not
require a conventional special mold, and complicated manufacturing
steps. The molding cycle time and manufacturing costs are
significantly reduced. Furthermore, since the sandwich-molded guide
does not require a steel sheet or the like as a core material, the
weight of the guide is substantially reduced, and the molded guide
of the invention can contribute to a reduction in fuel cost, and a
reduction in vibration noise by suppression of vibration energy.
Additionally, since the entire sandwich-molded guide consists of
polymer resins, they need not be disassembled or separated after
their removal from the transmission device, and recycling is
thereby facilitated.
[0037] Since two kinds of fused polymer resins are simultaneously
or substantially simultaneously injected and integrally joined with
each other in a fully fused condition, high strength properties of
the first polymer resin and the wear resistance of the second
polymer resin can complement each other. The first polymer resin
and the second polymer resin can be selected, taking into account
the relationships between their wear resistance and high strength
properties, and the high temperature environmental conditions to be
encountered in an automobile engine or the like.
[0038] Since the outer surface of the slide rail and the rail
support, which are integrally molded from a high strength first
polymer resin, is entirely covered by a wear-resistant second
polymer resin, the strength of the slide rail and the rail support
is reinforced by the skin of second polymer resin, and the
sandwich-molded guide of the invention exhibits excellent
durability. Therefore, the wear resistance required for the slide
rail, and the strength required for the rail support portion, can
be compatibly maintained at a high level over a long period of time
under high temperature environment such as found inside an
automobile engine.
[0039] Additionally, the surface layer of the boss and mounting
hole, provided at one end of the rail support for mounting the
movable guide, are injection-molded from a second polymer resin
material having wear resistance. Accordingly, the sandwich-molded
guide can function smoothly over a long period of time as a
pivotally movable guide to maintain proper tension in a chain or
other transmission medium.
* * * * *